diff --git a/library/HTMLPurifier/ConfigSchema/Interchange.php b/library/HTMLPurifier/ConfigSchema/Interchange.php
index 1b1a2489..18866dbf 100644
--- a/library/HTMLPurifier/ConfigSchema/Interchange.php
+++ b/library/HTMLPurifier/ConfigSchema/Interchange.php
@@ -22,14 +22,20 @@ class HTMLPurifier_ConfigSchema_Interchange
      * Adds a namespace array to $namespaces
      */
     public function addNamespace($namespace) {
-        $this->namespaces[$namespace->namespace] = $namespace;
+        if (isset($this->namespaces[$i = $namespace->namespace])) {
+            throw new HTMLPurifier_ConfigSchema_Exception("Cannot redefine namespace '$i'");
+        }
+        $this->namespaces[$i] = $namespace;
     }
     
     /**
      * Adds a directive array to $directives
      */
     public function addDirective($directive) {
-        $this->directives[$directive->id->__toString()] = $directive;
+        if (isset($this->directives[$i = $directive->id->__toString()])) {
+            throw new HTMLPurifier_ConfigSchema_Exception("Cannot redefine directive '$i'");
+        }
+        $this->directives[$i] = $directive;
     }
     
 }
diff --git a/library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php b/library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php
index 6020e573..f010cdfc 100644
--- a/library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php
+++ b/library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php
@@ -15,6 +15,12 @@ class HTMLPurifier_ConfigSchema_InterchangeBuilder
      * @param $hash HTMLPurifier_ConfigSchema_StringHash source data
      */
     public function build($interchange, $hash) {
+        if (!$hash instanceof HTMLPurifier_StringHash) {
+            $hash = new HTMLPurifier_StringHash($hash);
+        }
+        if (!isset($hash['ID'])) {
+            throw new HTMLPurifier_ConfigSchema_Exception('Hash does not have any ID');
+        }
         if (strpos($hash['ID'], '.') === false) {
             $this->buildNamespace($interchange, $hash);
         } else {
@@ -26,7 +32,9 @@ class HTMLPurifier_ConfigSchema_InterchangeBuilder
     public function buildNamespace($interchange, $hash) {
         $namespace = new HTMLPurifier_ConfigSchema_Interchange_Namespace();
         $namespace->namespace   = $hash->offsetGet('ID');
-        $namespace->description = $hash->offsetGet('DESCRIPTION');
+        if (isset($hash['DESCRIPTION'])) {
+            $namespace->description = $hash->offsetGet('DESCRIPTION');
+        }
         $interchange->addNamespace($namespace);
     }
     
@@ -35,33 +43,43 @@ class HTMLPurifier_ConfigSchema_InterchangeBuilder
         
         // These are required elements:
         $directive->id = $this->id($hash->offsetGet('ID'));
-        $type = explode('/', $hash->offsetGet('TYPE'));
-        if (isset($type[1])) $directive->typeAllowsNull = true;
-        $directive->type = $type[0];
-        $directive->description = $directive->offsetGet('DESCRIPTION');
         
-        // These are extras:
-        if (isset($directive['ALLOWED'])) {
-            $directive->allowed = $this->lookup($this->evalArray($directive->offsetGet('ALLOWED')));
+        if (isset($hash['TYPE'])) {
+            $type = explode('/', $hash->offsetGet('TYPE'));
+            if (isset($type[1])) $directive->typeAllowsNull = true;
+            $directive->type = $type[0];
         }
-        if (isset($directive['VALUE-ALIASES'])) {
-            $directive->valueAliases = $this->evalArray($directive->offsetGet('VALUE-ALIASES'));
+        
+        if (isset($hash['DESCRIPTION'])) {
+            $directive->description = $hash->offsetGet('DESCRIPTION');
         }
-        if (isset($directive['ALIASES'])) {
+        
+        if (isset($hash['ALLOWED'])) {
+            $directive->allowed = $this->lookup($this->evalArray($hash->offsetGet('ALLOWED')));
+        }
+        
+        if (isset($hash['VALUE-ALIASES'])) {
+            $directive->valueAliases = $this->evalArray($hash->offsetGet('VALUE-ALIASES'));
+        }
+        
+        if (isset($hash['ALIASES'])) {
             $raw_aliases = trim($hash->offsetGet('ALIASES'));
             $aliases = preg_split('/\s*,\s*/', $raw_aliases);
             foreach ($aliases as $alias) {
-                $this->aliases[] = $this->id($alias);
+                $directive->aliases[] = $this->id($alias);
             }
         }
-        if (isset($directive['VERSION'])) {
-            $directive->version = $directive->offsetGet('VERSION');
+        
+        if (isset($hash['VERSION'])) {
+            $directive->version = $hash->offsetGet('VERSION');
         }
-        if (isset($directive['DEPRECATED-USE'])) {
-            $directive->deprecatedUse = $this->id($directive->offsetGet('DEPRECATED-USE'));
+        
+        if (isset($hash['DEPRECATED-USE'])) {
+            $directive->deprecatedUse = $this->id($hash->offsetGet('DEPRECATED-USE'));
         }
-        if (isset($directive['DEPRECATED-VERSION'])) {
-            $directive->deprecatedVersion = $directive->offsetGet('DEPRECATED-VERSION');
+        
+        if (isset($hash['DEPRECATED-VERSION'])) {
+            $directive->deprecatedVersion = $hash->offsetGet('DEPRECATED-VERSION');
         }
         
         $interchange->addDirective($directive);
diff --git a/library/HTMLPurifier/ConfigSchema/Validator.php b/library/HTMLPurifier/ConfigSchema/Validator.php
index 48c0f82a..88125877 100644
--- a/library/HTMLPurifier/ConfigSchema/Validator.php
+++ b/library/HTMLPurifier/ConfigSchema/Validator.php
@@ -11,7 +11,7 @@ class HTMLPurifier_ConfigSchema_Validator
     /**
      * Volatile context variables to provide a fluent interface.
      */
-    protected $context, $obj, $member;
+    protected $context = array(), $obj, $member;
     
     /**
      * Validates a fully-formed interchange object. Throws an
@@ -28,38 +28,53 @@ class HTMLPurifier_ConfigSchema_Validator
     }
     
     public function validateNamespace($n) {
-        $this->context = "namespace '{$n->namespace}'";
+        $this->context[] = "namespace '{$n->namespace}'";
         $this->with($n, 'namespace')
             ->assertNotEmpty()
             ->assertAlnum();
         $this->with($n, 'description')
-            ->assertIsString()
-            ->assertNotEmpty();
+            ->assertNotEmpty()
+            ->assertIsString(); // technically redundant
+        array_pop($this->context);
     }
     
     public function validateDirective($d) {
-        $this->context = "directive '{$d->id}'";
+        $this->context[] = "directive '{$d->id}'";
         $this->validateId($d->id);
+        $this->with($d, 'description')
+            ->assertNotEmpty();
+        if (!isset(HTMLPurifier_VarParser::$types[$d->type])) {
+            $this->error('type', 'is invalid');
+        }
+        array_pop($this->context);
     }
     
     public function validateId($id) {
-        $this->context = "id '$id'";
+        $this->context[] = "id '$id'";
+        if (!isset($this->interchange->namespaces[$id->namespace])) {
+            $this->error('namespace', 'does not exist');
+        }
         $this->with($id, 'namespace')
             ->assertNotEmpty()
             ->assertAlnum();
         $this->with($id, 'directive')
             ->assertNotEmpty()
             ->assertAlnum();
+        array_pop($this->context);
     }
     
     // protected helper functions
     
     protected function with($obj, $member) {
-        return new HTMLPurifier_ConfigSchema_ValidatorAtom($this->context, $obj, $member);
+        return new HTMLPurifier_ConfigSchema_ValidatorAtom($this->getFormattedContext(), $obj, $member);
     }
     
-    protected function error($msg) {
-        throw new HTMLPurifier_ConfigSchema_Exception($msg . ' in ' . $this->context);
+    protected function error($target, $msg) {
+        throw new HTMLPurifier_ConfigSchema_Exception(ucfirst($target) . ' in ' . $this->getFormattedContext() . ' ' . $msg);
+    }
+    
+    protected function getFormattedContext() {
+        return implode(' in ', array_reverse($this->context));
     }
     
 }
diff --git a/library/HTMLPurifier/ConfigSchema/ValidatorAtom.php b/library/HTMLPurifier/ConfigSchema/ValidatorAtom.php
index b799d67b..ac8d3e5d 100644
--- a/library/HTMLPurifier/ConfigSchema/ValidatorAtom.php
+++ b/library/HTMLPurifier/ConfigSchema/ValidatorAtom.php
@@ -40,7 +40,7 @@ class HTMLPurifier_ConfigSchema_ValidatorAtom
     }
     
     protected function error($msg) {
-        throw new HTMLPurifier_ConfigSchema_Exception('Member variable \'' . $this->member . '\' in ' . $this->context . ' ' . $msg);
+        throw new HTMLPurifier_ConfigSchema_Exception(ucfirst($this->member) . ' in ' . $this->context . ' ' . $msg);
     }
     
 }
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/descriptionNotEmpty.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/descriptionNotEmpty.vtest
new file mode 100644
index 00000000..fd2d0922
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/descriptionNotEmpty.vtest
@@ -0,0 +1,7 @@
+ERROR: Description in directive 'Ns.Dir' must not be empty
+----
+Ns
+DESCRIPTION: Our namespace.
+----
+Ns.Dir
+TYPE: int
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/idDirectiveAlnum.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/idDirectiveAlnum.vtest
new file mode 100644
index 00000000..9ffd143b
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/idDirectiveAlnum.vtest
@@ -0,0 +1,8 @@
+ERROR: Directive in id 'Ns.+' in directive 'Ns.+' must be alphanumeric
+----
+Ns
+DESCRIPTION: Generic namespace.
+----
+ID: Ns.+
+TYPE: int
+DESCRIPTION: Description
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/idDirectiveNotEmpty.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/idDirectiveNotEmpty.vtest
new file mode 100644
index 00000000..27e11282
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/idDirectiveNotEmpty.vtest
@@ -0,0 +1,8 @@
+ERROR: Directive in id 'Ns.' in directive 'Ns.' must not be empty
+----
+Ns
+DESCRIPTION: Our namespace
+----
+ID: Ns.
+TYPE: int
+DESCRIPTION: Description.
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/idNamespaceExists.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/idNamespaceExists.vtest
new file mode 100644
index 00000000..b216bf8d
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/idNamespaceExists.vtest
@@ -0,0 +1,5 @@
+ERROR: Namespace in id 'Rd.Dir' in directive 'Rd.Dir' does not exist
+----
+ID: Rd.Dir
+TYPE: int
+DESCRIPTION: Description
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeExists.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeExists.vtest
new file mode 100644
index 00000000..dd2ae907
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeExists.vtest
@@ -0,0 +1,8 @@
+ERROR: Type in directive 'Ns.Dir' is invalid
+----
+Ns
+DESCRIPTION: Namespace
+----
+Ns.Dir
+DESCRIPTION: Directive
+TYPE: foobar
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/unique.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/unique.vtest
new file mode 100644
index 00000000..7fbd4744
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/unique.vtest
@@ -0,0 +1,9 @@
+ERROR: Cannot redefine directive 'Ns.Dir'
+----
+ID: Ns.Dir
+DESCRIPTION: Version 1
+TYPE: int
+----
+ID: Ns.Dir
+DESCRIPTION: Version 2
+TYPE: int
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/namespace/descriptionNotEmpty.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/descriptionNotEmpty.vtest
new file mode 100644
index 00000000..888218a0
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/descriptionNotEmpty.vtest
@@ -0,0 +1,3 @@
+ERROR: Description in namespace 'Ns' must not be empty
+----
+ID: Ns
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/namespace/namespaceAlnum.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/namespaceAlnum.vtest
new file mode 100644
index 00000000..5b914f75
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/namespaceAlnum.vtest
@@ -0,0 +1,4 @@
+ERROR: Namespace in namespace 'R&D' must be alphanumeric
+----
+ID: R&D
+DESCRIPTION: ctype_alnum($ID) === false
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/namespace/namespaceNotEmpty.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/namespaceNotEmpty.vtest
new file mode 100644
index 00000000..42ba5baa
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/namespaceNotEmpty.vtest
@@ -0,0 +1,4 @@
+ERROR: Namespace in namespace '0' must not be empty
+----
+ID: 0
+DESCRIPTION: empty($ID) === true
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/namespace/normal.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/normal.vtest
new file mode 100644
index 00000000..13238143
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/normal.vtest
@@ -0,0 +1,2 @@
+Namespace
+DESCRIPTION: This is a generic namespace.
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/namespace/unique.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/unique.vtest
new file mode 100644
index 00000000..1d1f12d1
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/namespace/unique.vtest
@@ -0,0 +1,7 @@
+ERROR: Cannot redefine namespace 'Ns'
+----
+ID: Ns
+DESCRIPTION: Version 1
+----
+ID: Ns
+DESCRIPTION: Version 2
diff --git a/tests/HTMLPurifier/ConfigSchema/ValidatorAtomTest.php b/tests/HTMLPurifier/ConfigSchema/ValidatorAtomTest.php
index 7dc027f9..fe6cc262 100644
--- a/tests/HTMLPurifier/ConfigSchema/ValidatorAtomTest.php
+++ b/tests/HTMLPurifier/ConfigSchema/ValidatorAtomTest.php
@@ -19,7 +19,7 @@ class HTMLPurifier_ConfigSchema_ValidatorAtomTest extends UnitTestCase
     }
     
     public function testAssertIsStringFail() {
-        $this->expectValidationException("Member variable 'property' in context must be a string");
+        $this->expectValidationException("Property in context must be a string");
         $this->makeAtom(3)->assertIsString();
     }
     
@@ -28,7 +28,7 @@ class HTMLPurifier_ConfigSchema_ValidatorAtomTest extends UnitTestCase
     }
     
     public function testAssertNotNullFail() {
-        $this->expectValidationException("Member variable 'property' in context must not be null");
+        $this->expectValidationException("Property in context must not be null");
         $this->makeAtom(null)->assertNotNull();
     }
     
@@ -37,12 +37,12 @@ class HTMLPurifier_ConfigSchema_ValidatorAtomTest extends UnitTestCase
     }
     
     public function testAssertAlnumFail() {
-        $this->expectValidationException("Member variable 'property' in context must be alphanumeric");
+        $this->expectValidationException("Property in context must be alphanumeric");
         $this->makeAtom('%a')->assertAlnum();
     }
     
     public function testAssertAlnumFailIsString() {
-        $this->expectValidationException("Member variable 'property' in context must be a string");
+        $this->expectValidationException("Property in context must be a string");
         $this->makeAtom(3)->assertAlnum();
     }
     
@@ -51,7 +51,7 @@ class HTMLPurifier_ConfigSchema_ValidatorAtomTest extends UnitTestCase
     }
     
     public function testAssertNotEmptyFail() {
-        $this->expectValidationException("Member variable 'property' in context must not be empty");
+        $this->expectValidationException("Property in context must not be empty");
         $this->makeAtom('')->assertNotEmpty();
     }
     
diff --git a/tests/HTMLPurifier/ConfigSchema/ValidatorTest.php b/tests/HTMLPurifier/ConfigSchema/ValidatorTest.php
deleted file mode 100644
index 11404b38..00000000
--- a/tests/HTMLPurifier/ConfigSchema/ValidatorTest.php
+++ /dev/null
@@ -1,75 +0,0 @@
-<?php
-
-class HTMLPurifier_ConfigSchema_ValidatorTest extends UnitTestCase
-{
-    
-    protected $interchange, $validator;
-    
-    public function setup() {
-        $this->interchange = new HTMLPurifier_ConfigSchema_Interchange();
-        $this->validator   = new HTMLPurifier_ConfigSchema_Validator();
-    }
-    
-    /**
-     * Adds a namespace to our interchange object.
-     */
-    protected function addNamespace($namespace, $description) {
-        $obj = new HTMLPurifier_ConfigSchema_Interchange_Namespace();
-        $obj->namespace   = $namespace;
-        $obj->description = $description;
-        $this->interchange->addNamespace($obj);
-        return $obj;
-    }
-    
-    protected function addDirective($namespace, $directive, $type = 'string', $description = 'Description') {
-        $obj = new HTMLPurifier_ConfigSchema_Interchange_Directive();
-        $obj->id = $this->makeId($namespace, $directive);
-        $obj->type = $type;
-        $obj->description = $description;
-        $this->interchange->addDirective($obj);
-        return $obj; // for future editing
-    }
-    
-    protected function makeId($namespace, $directive) {
-        return new HTMLPurifier_ConfigSchema_Interchange_Id($namespace, $directive);
-    }
-    
-    /**
-     * Invokes a validation, so we can fish for exceptions
-     */
-    protected function validate() {
-        $this->validator->validate($this->interchange);
-    }
-    
-    protected function expectValidationException($msg) {
-        $this->expectException(new HTMLPurifier_ConfigSchema_Exception($msg));
-    }
-    
-    public function testNamespace() {
-        $this->addNamespace('Namespace', 'This is a generic namespace');
-        $this->validate();
-    }
-    
-    public function testNamespaceNamespaceNotEmpty() {
-        $this->addNamespace('0', 'Description');
-        $this->expectValidationException("Member variable 'namespace' in namespace '0' must not be empty");
-        $this->validate();
-    }
-    
-    public function testNamespaceNamespaceAlnum() {
-        $this->addNamespace('%', 'Description');
-        $this->expectValidationException("Member variable 'namespace' in namespace '%' must be alphanumeric");
-        $this->validate();
-    }
-    
-    public function testNamespaceDescriptionNotEmpty() {
-        $this->addNamespace('Ns', '');
-        $this->expectValidationException("Member variable 'description' in namespace 'Ns' must not be empty");
-        $this->validate();
-    }
-    
-    public function testDirectiveIdNamespaceNotEmpty() {
-        $this->addDirective('', 'Dir');
-    }
-    
-}
diff --git a/tests/HTMLPurifier/ConfigSchema/ValidatorTestCase.php b/tests/HTMLPurifier/ConfigSchema/ValidatorTestCase.php
new file mode 100644
index 00000000..eb016eed
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/ValidatorTestCase.php
@@ -0,0 +1,42 @@
+<?php
+
+/**
+ * Controller for validator test-cases.
+ */
+class HTMLPurifier_ConfigSchema_ValidatorTestCase extends UnitTestCase
+{
+    
+    protected $_path, $_parser, $_builder;
+    public $validator;
+    
+    public function __construct($path) {
+        $this->_path = $path;
+        $this->_parser  = new HTMLPurifier_StringHashParser();
+        $this->_builder = new HTMLPurifier_ConfigSchema_InterchangeBuilder();
+        parent::UnitTestCase($path);
+    }
+    
+    public function setup() {
+        $this->validator = new HTMLPurifier_ConfigSchema_Validator();
+    }
+    
+    public function testValidator() {
+        $hashes = $this->_parser->parseMultiFile($this->_path);
+        $interchange = new HTMLPurifier_ConfigSchema_Interchange();
+        $error = null;
+        foreach ($hashes as $hash) {
+            if (!isset($hash['ID'])) {
+                if (isset($hash['ERROR'])) {
+                    $this->expectException(
+                        new HTMLPurifier_ConfigSchema_Exception($hash['ERROR'])
+                    );
+                }
+                continue;
+            }
+            $this->_builder->build($interchange, new HTMLPurifier_StringHash($hash));
+        }
+        $this->validator->validate($interchange);
+        $this->pass();
+    }
+    
+}
diff --git a/tests/common.php b/tests/common.php
index 31820d19..9fc987ff 100644
--- a/tests/common.php
+++ b/tests/common.php
@@ -156,6 +156,8 @@ function htmlpurifier_add_test($test, $test_file, $only_phpt = false) {
         case '.php':
             require_once $test_file;
             return $test->addTestClass(path2class($test_file));
+        case '.vtest':
+            return $test->addTestCase(new HTMLPurifier_ConfigSchema_ValidatorTestCase($test_file));
         default:
             trigger_error("$test_file is an invalid file for testing", E_USER_ERROR);
     }
diff --git a/tests/index.php b/tests/index.php
index b045b804..cfd6bf4c 100755
--- a/tests/index.php
+++ b/tests/index.php
@@ -110,6 +110,14 @@ foreach ($test_dirs as $dir) {
     }
 }
 
+// handle vtest dirs
+foreach ($vtest_dirs as $dir) {
+    $raw_files = $FS->globr($dir, '*.vtest');
+    foreach ($raw_files as $file) {
+        $test_files[] = str_replace('\\', '/', $file);
+    }
+}
+
 // handle phpt files
 foreach ($phpt_dirs as $dir) {
     $phpt_files = $FS->globr($dir, '*.phpt');
diff --git a/tests/test_files.php b/tests/test_files.php
index 210112e2..def93e22 100644
--- a/tests/test_files.php
+++ b/tests/test_files.php
@@ -15,6 +15,10 @@ if (!$AC['only-phpt']) {
       $test_files[] = 'HTMLPurifier/Filter/ExtractStyleBlocksTest.php';
     }
     
+    // ConfigSchema Validator tests
+    $vtest_dirs = array();
+    $vtest_dirs[] = 'HTMLPurifier/ConfigSchema/Validator';
+    
     // ConfigDoc auxiliary library
     if (version_compare(PHP_VERSION, '5.2', '>=')) {
         $test_dirs[] = 'ConfigDoc';